Add diagnostics facility

1 files changed, 41 insertions, 0 deletions

diff --git a/butl/diagnostics.cxx b/butl/diagnostics.cxx
new file mode 100644
index 0000000..e4c22dc
--- /dev/null
+++ b/butl/diagnostics.cxx
@@ -0,0 +1,41 @@
+// file      : butl/diagnostics.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#include <butl/diagnostics>
+
+#include <iostream> // cerr
+
+using namespace std;
+
+namespace butl
+{
+  ostream* diag_stream = &cerr;
+
+  void diag_record::
+  flush () const
+  {
+    if (!empty_)
+    {
+      *diag_stream << os.str () << endl;
+      empty_ = true;
+
+      if (epilogue_ != nullptr)
+        epilogue_ (*this); // Can throw.
+    }
+  }
+
+  diag_record::
+  ~diag_record () noexcept (false)
+  {
+    // Don't flush the record if this destructor was called as part of
+    // the stack unwinding. Right now this means we cannot use this
+    // mechanism in destructors, which is not a big deal, except for
+    // one place: exception_guard. So for now we are going to have
+    // this ugly special check which we will be able to get rid of
+    // once C++17 uncaught_exceptions() becomes available.
+    //
+    if (!std::uncaught_exception () || exception_unwinding_dtor)
+      flush ();
+  }
+}